﻿using System;

/*
  Write a program that calculates N!/K! for given N and K (1<N<K).
 */

class FactorialsTest1
{
    static void Main(string[] args)
    {
        Console.Write("Enter K ( 1 < K ) : ");
        uint k = Convert.ToUInt32(Console.ReadLine());
        Console.Write("Enter N ( 1 < N < K ) : ");
        uint n = Convert.ToUInt32(Console.ReadLine());
        if( (k < 1) || (n < 1) || (k <= n) ) 
        {
            Console.WriteLine("Invalid input!");
        }
        else
        {
            double result = 1;
            for (uint i = n+1; i <= k; i++)
            {
                result /= i;
            }

            Console.WriteLine("{0}!/{1}! = {2}", n, k, result);
        }

    }
}

